5.56 NATO GP RH 4150 CrMoV, Nitride | Selectable
5.56 NATO GP RH 4150 CrMoV, Nitride | Selectable, Match-quality Nitromet(TM) 5.56 GP barrel, has been treated with Nitromet(TM) (salt bath nitrocarburized) inside and out with a hardened finish that results in a bore life 40% greater than with traditional chrome-lining without affecting accuracy. Barrels are made of 4150 Chrome Moly Vanadium steel, chambered for 5.56mm NATO, button rifled with 1-7 twist rifling, and machined to a standard M4 profile. Gas port drilled for a carbine length gas system, .750 diameter at the gas block. . Comes with a Ni